In automotive engines, vacuum developed within the intake manifold or produced by a vacuum generator (e.g., a vacuum pump or aspirator) is routinely used to power pneumatic accessories such as power brake boosters. On/off operation of the generator and/or accessory is frequently controlled by a gate valve in which a rigid gate is deployed across a conduit to stop the flow of a fluid (in this exemplary application, air) through the valve. Within automated or “commanded” valves, the gate is typically actuated by a solenoid and opened or closed in response to an electrical current applied to the solenoid coil. These solenoid-powered gate valves also tend to include a coil spring, diaphragm, or other biasing element which biases the gate towards an unpowered, ‘normally open’ or ‘normally closed’ position. Since the biasing force must overcome frictional forces resisting movement of the gate in order to return it to its normal position, and since the solenoid mechanism must overcome both these same frictional forces and any biasing force in order to move the gate to an actively-powered position, frictional forces tend to dictate much of the required solenoid operating force, i.e., the more friction, a larger/more powerful solenoid is required.
A good seal typically requires some degree of interference between the gate and the walls of the conduit. Thus, increasing the design's interference to obtain a reliable, high quality seal (especially when accounting for component variation within reasonable tolerances) tends to increase both the frictional forces resisting movement of the gate and the required solenoid operating force. However, if seal reliability and quality could be maintained with lower frictional resistance, reductions in solenoid operating force would beneficially allow for a reduction in the size, weight, and heat-dissipation requirement of the solenoid mechanism, and thus for a reduction in the size, weight, and power demand of the gate valve as a whole.